The sunvisor is mounted on a foreside windscreen of an automobile, it can prevent the sunlight from irritating to human eyes, and may be laid down or adjusted to a suitable angel by a driver himself. At present, some outlaws may lay down the sunvisor at night, to obscure their facial features by using shielding of the sunvisor, and to prevent their facial features being shot by a vehicle security system, thereby avoiding legal sanctions. In order to alert such case in advance and to promptly feedback dubiety of the vehicle and thus effectively provide reference information to the police, a rapid and effective detection to the vehicle sunvisor's state is necessary.
However, due to influence by the objective factors such as road complexity and environment in vehicle, the existing method for detecting a vehicle sunvisor's state at night has the following problems: 1, the road texture has certain influences on the sunvisor detection; 2, an object with a similar shape (such as a rectangular object put in the vehicle, a label stuck on the window and etc.) is easy to be regarded as the sunvisor, resulting in a false detection; 3, due to its low practicality, it is difficult to be applied into an actual vehicle security system. These factors severely influence the detection efficiency and the detection precision of the sunvisor's state. Therefore, there is not a perfect and mature algorithm for sunvisor's state detection at night-time, which can be applied in an actual situation.